1. Field of the Invention
The present invention relates to a carrying handle for a percussion power tool such as a hammer drill or a chisel hammer.
2. Description of the Prior Art
High-power hammer drills or chisel hammers having a mass of more than 10 kg, such as used in the mining industry, usually are arranged, when used, on a bore support or a bore mount. Such power tools are designed for being carried by a person when carried from one site to another site. When used in the mining industry, the power tools are subjected to hard loads and have their bottom partially ground. The working tool, which is used with power tools of the type described above, has an axial flush channel extending at least partially along the working tool stem. The flush channel serves for conducting of cooling fluid and flushing medium such as, e.g., water, which is fed either centrally through the chuck or through a flush head that sealingly surrounds the working tool stem in the region of the flush opening of the tool stem.
European Publication EP-0 059 071 disclosed a percussion hand-held power tool in which a working tool, which is received in a chuck of the power tool with a possibility of a limited axial displacement and which has a circumferential band, is locked by a wire stirrup that is secured to the chuck.
U.S. Pat. No. 5,749,421 discloses a percussion power tool in which the working tool is axially locked by a pivotal, self-locking lever which is secured to the power tool chuck and the pivotal movement of which in the axial direction is limited. The lever has a radial stop nose that engages from beneath a circumferential band provided on the working tool. To this end, the sleeve-shaped chuck extends axially up to an area beneath the working tool band.
Swiss Pat. No. 613,393 discloses a hammer drill in which a hollow side handle, which also serves for the aspiration of dust, is air-tightly connected with a suction head that sealingly surrounds the working tool in the region of the suction opening.
U.S. Pat. No. 6,112,831 discloses a heavy chisel hammer with an offset handle frame the stirrup-shaped carrying handle of which extending transverse to the percussion direction above the hammer chuck, does not protect the bottom of the chuck from a contact with a support. At that, the handle frame that surrounds the power tool, is very bulky.
British Publication GB-2040210 discloses a wood chisel tool in which a side guide handle is provided on the chuck and which, in connection with a carrying stirrup, permits to suspend the chisel tool on the forearm of a user to be used for a one-arm operation. The guide handle does not protect the chuck. The guide handle is not suitable for carrying the chisel tool.
An object of the invention is to provide a multi-functional carrying handle for a heavy power tool and which is suitable for both, anatomically, for carrying the power tool and for protection of the bottom of the chuck from a direct contact with a support or a mount.
This and other objects of the present invention, which will become apparent hereinafter are achieved by providing an assembly including a flush head connectable with a chuck of a percussion power tool, and a carrying head that forms with the flush head a functional unit.
The carrying handle has a bottom that protects the chuck along its longitudinal extent from beneath and along which the chuck slides, whereby the chuck is protected at least from large contaminants.
Advantageously, the handle is formed as a stirrup-shaped closed handle, which makes it very stable and, thus, capable of withstanding of high loads.
The functional unit, which is formed of the carrying frame and the flush head, can be easily attached to the power tool housing, e.g., with screws.
Advantageously, the carrying handle extends in an direction toward the working tool tip and has both its legs arranged on the flush head. As a result, the force application point is located in front of the power tool which permits to carry the power tool, together with an elongate working tool, with one hand.
Advantageously, the front, in the direction toward the working tool tip, leg of the stirrup-shaped carrying handle has an eyelet through which the working tool stem, together with the circumferential band, can be inserted, with the handle extending parallel to the percussion axis of the power tool.
Advantageously, on the working tool side of the carrying handle, there is provided locking means for the working tool that is capable of a limited axial displacement. The locking takes place outside of the chuck which permits to arrange the flush head between the chuck and the locking means. A possible idle impact on the working tool stem would be transmitted via the handle and the flush head to the power tool housing and would be absorbed thereby.
Advantageously, the locking means is formed as a locking cup pivotable in a direction toward the power tool but a pivotal movement of which in opposite direction is limited by the carrying handle. The locking cup engages from beneath, with its edge, which is located adjacent to the percussion axis, the radially projecting band formed on the stem of the working tool, locking the working tool. Advantageously, there is provided a spring for preloading the locking cup, which insures an automatic locking of the working tool.
The flush head has an inlet opening for flushing fluid and oriented toward the power tool. The inlet opening opens into a circumferential groove formed in the chuck, with the chuck being sealed, on opposite axial sides of the groove, with coaxial seals. The chuck forms an annular or circumferential space in the axial region of which, a radial opening of the working tool that communicates with a flush channel formed in the stem, is located. The radial opening is likewise sealed on its opposite sides. This provides for feeding of the flush medium directly into the flush head and therefrom into the working tool stem and to the drilling head.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiment, when read with reference to the accompanying drawing.